THIS invention relates to a method of treating value-bearing material comprising oxidised minerals. The method has particular application in the recovery of base and precious metal minerals. The invention also relates to an installation for carrying out the method.
The production and subsequent use of base and precious metals from their associated minerals plays an important role in the technological and economic well-being of society. In the separation processes commonly employed to recover these base and precious metal minerals, oxidised surfaces significantly impact upon the efficacy of such processes. These oxidised mineral surfaces most commonly arise through the oxidation processes that occur during the weathering of a sulfidic ore-body, however they can also occur during the mining and processing of that ore-body, forming both oxidised and surface oxidised minerals.
One solution that has been successfully applied to some oxidised minerals, typically malachite, cerussite and heterogeneite, has been aqueous sulfidisation. In this approach, the oxidised surfaces are converted to a sulfide surface using a soluble sulfide or hydrosulfide salt and thus become amenable to recovery by conventional downstream processing operations that can exploit surface differences, such as froth flotation.
However, not all oxidised and surface oxidised minerals are amenable to sulfidisation, generally due to reasons associated with process kinetics. Not only do such difficult to treat minerals represent a valuable and unattainable resource, but without recovery they both directly and indirectly impact upon the financial viability of a mineral recovery operation involved in the exploitation of an ore-body. Moreover, minerals that are not recovered by the downstream process report to the tailings, and upon containment and continued exposure to the environment, oxidise and release poisonous base-metal ions and other contaminants such as acid.
It is an object of the invention to provide a method of treating oxidised minerals in order to render them amenable to recovery by further progressing, and an installation for carrying out the method.